*: use array_size() helper macro

Use the array_size() helper macro.  Replaces several instances of local
macros with the same definition.

Reviewed-by: Scott Feldman <sfeldma@cumulusnetworks.com>
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/babeld/babel_main.c b/babeld/babel_main.c
index 2f3b555..7b1d879 100644
--- a/babeld/babel_main.c
+++ b/babeld/babel_main.c
@@ -444,7 +444,7 @@
         },
     };
 
-    signal_init (master, Q_SIGC(babel_signals), babel_signals);
+    signal_init (master, array_size(babel_signals), babel_signals);
 }
 
 static void